Could you check whether you can activate the McAfee Web Advisor extension on the Add-ons page. Either: * Ctrl+Shift+a (Mac: Command+Shift+a) * "3-bar" menu button (or Tools menu) > Add-ons * type or paste '''about:addons''' in the address bar and press Enter/Return In the left column of the Add-ons page, click Extensions. Then find McAfee on the right side and try its Enable button. Does that work? You probably need to reload any currently open page (Ctrl+r) to force Firefox to run it past the extension.